Surface and subsurface characteristics of the Çankırı Basin (Central Anatolia, Turkey): Integration of remote sensing, seismic interpretation and gravity

The geology of the Çankırı Basin has been studied using multi-source data including satellite images, aerial photos, gravimetric data and seismic sections, which are subsequently used to generate maps and a 3D model of that part of the basin covered by the seismic sections.

Surface and Subsurface Characteristics of the Çankırı Basin (Central Anatolia, Turkey): Integration of Remote Sensing,

Seismic Interpretation and Gravity

NURETDİN KAYMAKCI1, ŞENOL ÖZMUTLU2, PAUL M VAN DIJK3& YAKUP ÖZÇELİK4

1 RS/GIS Labaoratory, Department of Geological Engineering, Middle East Technical University,

TR−06531 Ankara, Turkey (E-mail: kaymakci@metu.edu.tr) 2

Vryhof Anchors B.V Rhijnspoor 255 2901 LB - PO Box 109 2900 AC, Capelle a/d IJssel, The Netherlands

3 ITC, Hengelosestr 99, P.O B0x 6, 7500 AA Enschede, The Netherlands 4

Turkish Petroleum Coorporation (TPAO), Söğütözü Caddesi No: 27, Söğütözü, TR−06520 Ankara, Turkey

Received 03 July 2008; revised typescript receipt 02 March 2009; accepted 04 March 2009

photos, gravimetric data and seismic sections, which are subsequently used to generate maps and a 3D model of that part of the basin covered by the seismic sections From the compilation, three different phases of deformation are recognized The earliest phase is characterized by thrusting during the Early Tertiary The second deformation phase is characterized by extensional deformation associated with normal faulting in the latest Early Miocene to Middle Miocene The third, and the last, phase is characterized by compressional deformation manifested by inversion of some

of pre-existing normal structures that has been taken took place since the Late Miocene Finally, the constructed model and the maps helped to better understand the 3D geometry and tectono-sedimentary evolution of the Çankırı Basin and the collisional history of the Sakarya Continent and the Kırşehir Block along the İzmir-Ankara-Erzincan Suture Zone.

Anatolia

Çankırı Havzası’nın Yüzey ve Yeraltı Jeolojisi (Orta Anadolu, Türkiye):

Uzaktan Algılama, Sismik Yorumlama ve Gravite Verilerinin Entegrasyonu

veri setleri kullanılarak çalışılmış ve elde edilen veriler havzanın değişik amaçlı haritaların hazırlanması ve sismik kesitlerin kapladığı kısmının ise 3 Boyutlu modelinin oluşturulmasında kullanılmıştır Derlenen verilerden havzanın üç farklı evrede deformasyona uğradığı anlaşılmıştır Erken Tersiyer dönemine tarihlenen en eski evre bindirme fayları ile karakterizedir Erken Miyosen sonu ile Orta Miyosen dönemine tarihlenen ikinci evre, normal faylanma ile ilişkili genişleme tektoniği ile karakterizedir Geç Miyosen’den itibaren etkin olan üçüncü ve son evre ise bir önceki evrede gelişmiş normal fayların terslenmesi ile kendini gösteren, sıkıştırmalı deformasyon ile karakterizedir Sonuç olarak, oluşturulan model ve haritalar, havzanın 3 Boyutlu geometrisi ile tektono-stratigrafik evrimi ve İzmir-Ankara-Erzincan Kenet Kuşağı boyunca meydana gelen Sakarya Kıtası ile Kırşehir Bloğunun çarpışma tarihçesinin daha iyi anlaşılmasını sağlamıştır

Orta Anadolu

The Çankırı Basin, one of the largest Tertiary basins

in Turkey (Figure 1), has possible economic

hydrocarbon and industrial mineral (mainly

evaporatic) reserves It lies within the

İzmir-Ankara-Erzincan Suture Zone (IAESZ) (Figure 1), which

demarcates the former position of the northern

branch of the Neotethys Ocean After consumption

of Neotethys, final collision occurred along the

IAESZ, during which the Sakarya continent of the

Pontides in the north amalgamated with the Kırşehir

Block in the south (Şengör & Yılmaz 1981; Görür et

al 1984; Robertson & Dixon 1984; Tüysüz &

Dellaloğlu 1992; Okay et al 1998; Robertson et al.

1996; Kaymakcı 2000; Kaymakcı et al 2000, 2003a,

b) The Çankırı Basin is a unique area in north

central Anatolia to study subduction and collision

processes owing to an almost 4-km-thick Upper

Cretaceous to recent in-fill, with only minor breaks

in sedimentation

The number of published geological studies in the

Çankırı Basin is relatively small This is due to

difficulty in dating continental deposits as well as the

geological complexity of the region, with a

superimposed, multi-deformational history

Recently, due to advances in digital technology and

improvements in geophysical and remote sensing

methods, the number of studies in the region has

increased For this purpose, the Turkish Petroleum

Co (TPAO, Ankara-Turkey) shot 24 seismic lines,

which amount to nearly 1000 km in line length

Improved gravity measurements were made available

by the General Directorate of Mineral Exploration

and Research Department (MTA, Ankara-Turkey)

The aim of this paper is to present the surface and

subsurface characteristics of the Çankırı Basin based

on satellite and airborne remote sensing, seismic

images, local gravity, and field studies in order to

understand better the subduction history of the

Neotethys and collisional and post collisional

processes along the İzmir-Ankara-Erzincan Suture

zone The remotely sensed data, combined with field

data and the published literature, were used to obtain

an up-to-date geological map of the basin The

seismic sections were interpreted and were used to

construct a 3D model for part of the basin The

gravity data were used to obtain gravity anomaly

images that were used to validate the generated 3Dmodel

Geological Background

The Çankırı Basin is located between the SakaryaContinent in the north and the Kırşehir Block in thesouth and is bounded in the west, north and east by

an ophiolitic mélange (North Anatolian OphioliticMélange, NAOM, cf Rojay 1995), associated withUpper Cretaceous volcano-sedimentary rockassemblages, which collectively constitute the rim ofthe basin (Figure 1) The same rock assemblagespartly underlie the infill of the Çankırı Basin in thenorth, and in the south it is underlain and delimited

by the Sulakyurt granitoids, forming thenorthernmost tip of the Kırşehir Block

The infill of the Çankırı Basin accumulated in 5different cycles of sedimentation (Figure 2) Theoldest cycle comprises Upper Cretaceous toPaleocene volcaniclastic rocks (Yaylaçayı andYapraklı formations), regressive shallow marineunits and Paleocene mixed environment red clasticsand carbonates (Dizilitaşlar, Kavak and Badiğinformations) In this paper, these are referred to as the

‘Upper Cretaceous units’ They are overlain by the

second cycle, which is a Paleocene to Oligoceneregressive flysch to molasse sequence referred to as

the ‘Tertiary clastics’ in this study In it a widespread thin (<100 m) ‘nummulitic limestone’ of Middle

Eocene age (Kocaçay Formation), that constitutesthe marker horizon in the seismic sections, passesupwards into very thick (up to 2000 m) MiddleEocene to Oligocene continental red clastics (İncikFormation) interfingering with and overlain byOligocene evaporites (Güvendik Formation) Thethird cycle is represented by fluvio-lacustrine clasticsdeposited in the Early to Middle Miocene, which,together with the Tortonian Tuğlu Formation are

referred to as the ‘Middle to Upper Miocene units’ in

this study The fourth cycle is represented by upperMiocene fluvio-lacustrine deposits which frequentlyalternate with evaporites (Tuğlu, Süleymanlı andBozkır formations) Plio−Quaternary alluvial fandeposits and recent alluvium locally overlie all theseunits (Figure 2)

The structures, which have played a role in thetectonic development of the Çankırı Basin, from

strike-slip faults thrust faults syncline,

ESFZ

GALA

TEAN VOLCANIC PROVINCE

NAFZ NAFZ

UUU RRR IIIDDD

Quaternary Pliocene

Paleocene Maastrichtian to Campanian

444 555

Td+Th Tkv

Tba

GS

Ty

Tm Tkg

Ttu Ts Tbo Tde Alluvium (Qal)

MN 13 MN10-12

Tb

NAOMNorth Anatolian Ophiolitic Melange

Ýncik

Dizilitaþlar and Hacýhalil formations (mainly turbidites and

Karabalçýk Formation (distributary channel

Karagüney Formation (clastics derived mainly from

Bayat

and volcanoclastics)

Osmankahya

clastics and red beds)

Kocaçay

‘marker horizon’

accretionary wedge, arc, fore-arc deposits

MN– ages of units in European mammal zones

oldest to youngest, are: (1) Compressional faults

(thrust and reverse faults with locally considerable

amounts of strike-slip component) situated mainly

along the rim of the basin (2) Dominantly

NE−SW-oriented strike-slip faults that cut the basin infill, the

basement, and the rim These include the presently

active Sungurlu Fault Zone (a sub strand of the

Ezinepazarı-Sungurlu Fault Zone), the

Yağbasan-Faraşlı Fault Zone and the Kızılırmak Fault Zone

(Figure 1c) (3) Other, but less pronounced

structures are normal faults concentrated mainly in

the central part of the basin and which have

displaced some of the compressional structures at

the rim (Figure 3)

The active tectonics of the Çankırı Basin area are

currently dominated by regional transcurrent

tectonics (Figure 1c), controlled by splay faults of the

North Anatolian Fault Zone (NAFZ) The NAFZ is

an approximately 1200-km-long strike-slip fault

zone that formed due northwards drift of the

Arabian Plate and its collision with the Eurasian

Plate (Şengör & Yılmaz 1981; Jackson & McKenzie

1984; Şengör et al 1985)

Remote Sensing

Two scenes from Landsat Thematic Mapper (TM)-5

images were used as a basis for the geological map of

the Çankırı Basin (Figures 3 & 4) The characteristics

of these images are given in Table 1 Before the

images were processed, a radiometric enhancement

(Lavreau 1992; Richard 1993) was carried out and

then they were mosaiced Subsequently, the portion

of the image covering the Çankırı Basin was

extracted from the mosaic for further analysis

A number of different image enhancement

techniques were performed to differentiate and map

each lithostratigraphic unit and to delineate the

geological structures These techniques include

simple linear contrast enhancement, decorrelation

stretch enhancement (Soha & Schwartz 1978;

Gillespie et al 1986), Intensity-Hue-Saturation

enhancement (Hayden 1982; Daily 1983; Grasso

1993) and Principal Component Analysis (Taylor

1974; Chavez & Kwarteng 1989) Since each

technique has its own strengths and weaknesses, they

could only enhance certain types of geological units

and none of the techniques had the ability todiscriminate all of the lithological units andstructures in one scene Therefore, duringinterpretation, all the above-mentionedenhancements were used to identify the units andstructures in a GIS medium However, decorrelationstretching technique with band combination of Red:

5, Green: 3, and Blue: 1 produced the optimumenhanced image to show most of the structures andalmost all units Therefore, final interpretation andtracing of the boundaries and plotting of structureswere performed on this image while the otherprocessed images were used in support The imageand the resultant map are presented in Figures 3 and

4

Image Interpretation

The interpretation of the images and the aerialphotos was performed in three successive steps Inthe first step before fieldwork, published maps were

used to support interpretation (Akyürek et al 1980; Dellaloğlu et al 1992; Özçelik & Savun 1993; Özçelik

1994) The resulting interpreted map was verifiedduring field studies In areas where sufficientresolution could not be achieved, due to the smallscale of the structures and/or the intensity of thedeformation, field mapping was performed using1:25.000 scale topographical maps Then the imageswere re-interpreted and verified in the successivefieldwork seasons This procedure (Figure 5) wasrepeated four times and verified in the field until afinal map was produced In the final map (Figure 4),the formation boundaries, faults, folds and the

photo-lineaments (O’Leary et al 1976) were traced

using on-screen digitizing directly onto the imageusing advanced cartographic techniques Hardcopieswere only utilized during field verification

Using remote sensing and field data, twenty-eightformations, plus the alluvium, were recognized andmapped (Figure 4) Six of these formations arerecognized for the first time in this study These are,

in stratigraphic order, upper Cretaceous quartz-latitemember of the NAOM, upper Cretaceous toPaleocene Kavak and Badiğin formations, theMiddle Eocene to Oligocene İncik Formation, whichwas separated into two units (Ti1 and Ti2) although

reverse and thrust faultssyncline

transpressional/transtensional and strike-slip faultsanticline

normal faultsoverturne syncline

KIZILIRMAK

TUÐLU

SUNGURLU

SARIYAKA SULAKYURT

KIRIKKALE KALECÝK

HANCILI

folds and photo-lineaments are overlaid on the image.

in the field they could not be differentiated clearly,

the Oligocene Güvendik Formation and Tortonian

Tuğlu Formation, which had previously been

mapped as a single unit In addition, the Kılçak,

Altıntaş, Hancılı, and Çandır formations, which werepartly recognized by previous researchers, have beenseparated and mapped out for the first time in thisstudy

Lineament Analysis

Photo-lineaments are defined as simple or composite

linear features on the earth’s surface which can be

recognized on maps or on satellite images, must be

mappable for at least a few kilometres length and

which have a rectilinear or slightly curvilinear

geometry and presumably reflect subsurface

phenomena (O’Leary et al 1976; Park & Jaroszewski

1994) These lineaments (Figure 6) were categorized

into two classes based on their quality Only those

with appreciable offset are classified as ‘faults’ and

were analyzed together with the faults that are

verified in the field (see Kaymakcı et al 2000, 2003a).

The others are classified as photo-lineaments In the

analyses, the Çankırı Basin was divided into 11

sub-areas (Figure 6), based on variation in structural

trends and the geometry of the basin rim For each

sub-area, length weighted rose diagrams for the

faults and the photo lineaments were prepared and

compared

Spatial Characteristics of the Lineaments

Apart from the differences in the orientations of the

lineaments, there is also a difference in their

distribution in the study area The lineaments are

concentrated mainly in the rim of the basin and in

the pre-Neogene units The southern sub-areas (subareas 3, 4, 5 and 9) have the highest frequency offaults, while the western sub-areas (sub areas 1 to 3)have the highest frequency of photo-lineaments(Tables 2 & 3) Sub-area 7 has the least frequency offaults, and, considering its size, the photo-lineamentsare also fewer than in other parts of the ÇankırıBasin (Figure 6)

Tectonic Implications of the Lineaments

The domination of the lineaments within the Neogene units may indicate that these units were

pre-subjected to deformation phases (Kaymakcı et al.

2000, 2003a) that did not affect the Neogene units It

is obvious that the younger rocks are exposed tofewer deformation phases, as in sub-area 7 wheremainly Late Miocene formations are exposed The rose diagrams prepared for all the faults andfor the photo-lineaments display a Riedel geometricpattern (Figure 9b) in which all components of theRiedel shears are developed and displayed In thispattern the Sungurlu, Kızılırmak, and Yağbasan-Faraşlı fault zones constitute the y-shears TheEldivan Fault Zone (EFZ), which defines the westernmargin of the Çankırı Basin (sub-areas 1−3), isalmost parallel to the orientation of the expectedcompressional structures (f in Figure 7) in a Riedelsystem, although, it slightly deviates from it(approximately 15° anticlockwise)

of the processed gravity data is illustrated in Figure 8

In the processed gravity image, the rim of thebasin, the granitoids of the Kırşehir Block, and twoburied (blind) thrust belts (discussed below; one inthe central northern part and one in the easternmargin), are expressed respectively as a positiveanomaly with respect to the basin in-fill (Figure 8)

In addition, a NE−SW-trending fault that dextrallydisplaces the northern margin of the Çankırı Basin is

01 September 1984

Coordinates of studied portion (UTM ZONE 36)

FIELD STUDIES

1 verification of lithological and structural interpretations

simple contrast stretching

principal component analysis

de-correlation stretching

1:60.000 & 1:35.000 scale

PUBLISHED MAPS 1:100.000 (i, ii, iii) 1: 50.000 (ii, iii) 1:25.000 (ii, iii)

GEOLOGICAL MAP

of the Çankýrý Basin

published maps: i Dellaloðlu et al (1992), ii Akyürek et al (1980), iii Özçelik & Savun (1993)

i-iii indicate the references of the published maps (i) Dellaloğlu et al (1992), (ii) Akyűrek et al (1980), (i-iii)

Őzçelik & Savun (1993).

recognized This fault is seen only in the

pre-Neogene units (Figures 4 & 6) but can be traced

below the cover of Neogene units for a considerable

distance (approximately 30 km) on the processed

gravity image In the southern part of the basin, the

Yağbasan-Faraşlı Fault Zone and the main strand of

the Sungurlu Fault Zone (YFFZ and MSFZ,respectively) are delineated on the gravity image(Figure 8) Pseudo-stereo shaded relief imagesfacilitate 3-D visualization of thickness variation ofthe infill and help the identification of the structures,chiefly including the outline of the rim, the

Table 2 Percentages of the faults in the subareas.